In a video system which utilizes a repositionable solid state sensor for generating image signals from a photographic image, it may be necessary to align the sensor with the photographic image prior to, for example, initial power up from the video system.
For example, in U.S. application Ser. No. 07/143,661, now U.S. Pat. No. 4,819,073, entitled "Film Video Player Apparatus", an apparatus for sensing a photographic color film and for converting a sensed photographic image into a video signal is disclosed. The above identified application deals with a film player in which relative vertical, horizontal and rotational translation is effected between the photographic image and a CCD imaging sensor. This application is assigned to the assignee of the present invention, and the contents of this application are incorporated herein by reference.
A conventional approach to the design of film video players contemplates the use of fixed apparatus for mounting a slide or negative (representing a film image) and a fixed sensor which is spaced a distance therefrom along the optical axis of the system. Interposed between the fixed film image and the fixed sensor is a multi-group variable focal length lens wherein one of the lens elements is movable axially along the optical axis to vary the focal length of the lens and thus provide a zoom capability. Such multi-group variable focal length lenses normally require the driving of a plurality of cam surfaces to effect the zoom functions. This can result in an intricate and expensive mechanism.
To overcome these and other problems, the film video player of the incorporated application includes at least one film gate for mounting photographic film in relation to an imaging mechanism having a lens for projecting at least a portion of a film image onto an imaging sensor. The sensor converts the sensor image to an electrical signal which is then converted to a video signal for display of the image on a monitor. The film player includes a zoom mechanism for changing the magnification of the sensor image with respect to the film image and a scan mechanism for translating the sensor with respect to the film image in a first direction. Also included are a gear assembly for both translating the sensor with respect to the film image in a second direction which is perpendicular to the first direction, and for rotating the sensor with respect to the film image.
In this system due to misalignment of the repositionable sensor and the photographic image (which is typically in the form of a negative or slide), it may be necessary to align the sensor with the film image in order to generate a proper video display. More specifically, accidental misalignment between the photographic image and sensor may occur during transportation of the film video player. Misalignment also may occur, for example, when the film video player is shut off after use in a condition where the system has been zoomed to focus on a corner of the photographic image. To overcome this misalignment, an exemplary embodiment of the present invention provides for alignment of the repositionable sensor with the film image during initial power up of the film video player using the image of a pixel mask lying in a plane displaced from (or, alternatively, coincident with) the plane of the film image.
The invention is suitable for transfering to video an image on a photographic medium such as a film or a print. In the former case, light from the source is transmitted through the photographic medium to the sensor while in the latter case light from the source is reflected from the image-bearing surface of the print to the sensor.